All coins struck in this new composition have a small "P" below the profile of the Queen on the obverse side.

While these coins did not come into common circulation until 2001, a small number of "P" test tokens were struck in 1999 and 2000. The tokens were given to vending machine companies and transit authorities to allow them to modify their machines to accept the new weight of the coin. A fair number of these test tokens are available on the collecting market, and (as of 1/21/2004) their price can range from US$2 - $10. The 2000 test tokens are scarcer than the 1999 tokens.

In late 2000 the Mint began the changeover to steel plated blanks, intending to begin striking the "P" coins for 2001. However, a shortage of 5-cent coins in Alberta and Quebec late in 2000 forced the Mint to issue an emergency supply of new nickels, which were struck with the new steel plated blanks. Approximately 2 million of these 2000P nickels are in circulation.

The 2001 "P" 25-cent coin is the first coin of that denomination to be issued with the well-known caribou profile since 1996.

The occurrence of errors such as die cracks and hairlines has increased since the mint began using the new plated steel composition. In fact, noticeable delays have occurred in issuing new coins and it is thought that the Mint is having difficulty mass producing coins with the new composition.

Update, on the meaning of the "P"
Vending machine companies requested a way to identify the new coins and some say that is the reason for the P mark on the coins, although this doesn't seem very plausible.

Other sources say the P indicates "plated", which seems more plausible since this type of coin is steel plated with other alloys.